function Stack() {
    var items = [];

    this.push = function(element) {
        items.push(element);
    };

    this.pop = function() {
        return items.pop();
    };

    this.peek = function() {
        return items[items.length - 1];
    };

    this.isEmpty = function() {
        return items.length === 0;
    };

    this.size = function() {
        return items.length;
    };

    this.clear = function() {
        items = [];
    };

    this.print = function() {
        console.log(items.toString());
    };
}